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Output of a computer model of underwater acoustic propagation in a simplified ocean environment. A seafloor map produced by multibeam sonar. Underwater acoustics (also known as hydroacoustics) is the study of the propagation of sound in water and the interaction of the mechanical waves that constitute sound with the water, its contents and its boundaries.
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At 20 °C (68 °F), the speed of sound in air, is about 343 m/s (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn), or 1 km in 2.91 s or one mile in 4.69 s.
Figure 1. Table 1's data in graphical format. Although given as a function of depth [note 1], the speed of sound in the ocean does not depend solely on depth.Rather, for a given depth, the speed of sound depends on the temperature at that depth, the depth itself, and the salinity at that depth, in that order.
The SOFAR channel (short for sound fixing and ranging channel), or deep sound channel (DSC), [1] is a horizontal layer of water in the ocean at which depth the speed of sound is at its minimum. The SOFAR channel acts as a waveguide for sound, and low frequency sound waves within the channel may travel thousands of miles before dissipating.
Sonar (sound navigation and ranging or sonic navigation and ranging) [2] is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances , communicate with or detect objects on or under the surface of the water, such as other vessels.
Underwater acoustic communication is a technique of sending and receiving messages in water. [1] There are several ways of employing such communication but the most common is by using hydrophones . Underwater communication is difficult due to factors such as multi-path propagation , time variations of the channel, small available bandwidth and ...
Upsweep is an unidentified sound detected on the American NOAA's equatorial autonomous hydrophone arrays. This sound was present when the Pacific Marine Environmental Laboratory began recording its sound surveillance system, SOSUS, in August 1991. It consists of a long train of narrow-band upsweeping sounds of several seconds in duration each.
If the distance from the transducer to the reflector is known, and the time taken from the transmit to the receive pulse is known, then the speed of sound in water can be calculated. Transducers used in sound velocity probes are typically of a high frequency (around 1 - 4 MHz) as the transmit and receive distances are close enough to mitigate ...